Towards optimal aerodynamic design of wind catchers: Impact of geometrical characteristics

Abstract

This paper presents a detailed parametric analysis of the impact of geometrical characteristics of wind catchers on their flow features to enhance the effectiveness of cross-ventilation strategies of buildings. The following geometrical characteristics are evaluated in detail: (i) ceiling tilt angle, (ii) radius of the outer-corner bend, (iii) leeward-side tilt angle, (iv) straight inlet extension length, (v) nozzle-shaped inlet extension radius, and (vi) radius of the inner-corner bend. In addition, the impact of using guide vanes in the bend of wind catchers is systematically investigated. High-resolution coupled (outdoor wind flow and indoor airflow) 3D steady RANS CFD simulations are performed for 40 different wind catcher geometries. The CFD simulations are based on a grid-sensitivity analysis and are validated by comparing with two wind-tunnel measurements. The results show that the use of straight and nozzle-shaped inlet extensions can significantly increase the airflow rate. The maximum increase is about 23%, which is achieved for the straight inlet extension length S/D = 1 (D is wind-catcher depth). Guide vanes are also found to effectively improve the flow uniformity inside wind catchers and significantly enhance the airflow rate. This enhancement can go up to 29% when guide vanes are implemented in combination with a straight inlet extension with S/D = 0.375. The results of the present study support the optimal aerodynamic design of wind catchers.